The fortress of Torre Velha is one of the more important examples of Renaissance-era military architecture, at a time when it served as part of an integrated system of defensive artillery outposts at the end of the 15th and beginning of the 16th century, in particular with the bulwarks of Tower of Santo António de Cascais (1498) and São Vicente (1512).

[1][2] Between 1580 and 1640 it was referred to locally as the Torre dos Castelhanos (Tower of the Castilians), where it was remodelled structurally to meet the requirements of the Philippine Dynasty.

[1] In a report written on 9 September 1794, by Guilherme Luís António de Valleré, directed to the Minister of War (Portuguese: Ministro da Guerra), the Duke of Lafões, it was indicated that the tower was undergoing restoration.

[1] Similarly, on 13 August 1814, it was determined that the Fort could serve as quarantine for lodging passengers and crews suspected of carrying contagious diseases.

[1][2] This included Rafael Bordalo Pinheiro who was suspected of having yellow fever, and was eventually sent to Brazil; the artist and humourist later made light of Portuguese regulations and poor treatment facilities.

On 29 May 1815, the fort was deactivated by order of the government, while part of its buildings were conserved as lodging for the security forces used to guard people in quarantine and those with leprosy.

[1] But, by 1894, the site was no longer used for this purpose, and began to serve as storage and housing (acting as an annex for the munitions warehouses of nearby Porto Brandão).

[1] The structure is located on Periurban, a hill on the southern shore of the Tagus River, between two small creeks, that of the Porto Brandão and Paulina, approximately opposite the Tower of Belém.

[1] Around the principal nucleus of the fortress is a second tier of spaces used for lodging; there are three bulwarks and barracks (one on the northeast, another along the southeast and a final one in the south, along the wall with cannons).

At the end of the 18th century, the fortress received new remodelling, possibly involving consolidation of the fortifications, under the supervision of Colonel Francisco D'Alincourt.